<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .progress {
            height: 25px;
            width: 400px;
            border-radius: 15px;
            background-color: #272425;
            border: 3px solid #272425;
            box-sizing: border-box;
            margin-bottom: 30px;
        }

        .inner {
            width: 50%;
            height: 20px;
            border-radius: 10px;
            text-align: right;
            position: relative;
            background-color: #409eff;
            background-size: 20px 20px;
            box-sizing: border-box;
            transition: all 1s;
        }

        .inner span {
            position: absolute;
            right: -20px;
            bottom: -25px;
        }
    </style>
</head>
<body>
<div id="app">
    <div class="progress">
        <div class="inner" :style="{'width':amount+'%'}">
            <span>{{ amount }}%</span>
        </div>
    </div>
    <button @click="amount=25">设置25%</button>
    <button @click="amount=50">设置50%</button>
    <button @click="amount=75">设置75%</button>
    <button @click="amount=100">设置100%</button>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    const app = new Vue({
        el: '#app',
        data: {
            amount: 0
        }
    })
</script>
</body>
</html>